The present invention relates to sensors of the type employed by robotic operators for sensing the load experienced by contacting a work article. In particular, the invention relates to electrically operated transducers employed for giving a robotic operator a sense of "feel", by providing electrically a signal indicative of the magnitude and location of the tactilely sensed force applied by the robotic operator contacting the work article.
An example of a tactile sensor or transducer for a robotic operator is that shown and described in copending application Ser. No. 672,544 filed Nov. 19, 1984 entitled "A New Concept for a Two-dimensional Tactile Sensor" which is assigned to the Assignee of the present invention. The aforementioned tactile sensor employs a load sensing plate simply supported by a plurality of spaced simple supports with each support strain gaged to indicate the individual reaction load experienced thereby upon contact of the plate with a work article. The output of the strain gages in the aforementioned device is processed by suitable known relationships for beam support to provide the sum of the individual support reaction loads to give the total load on the plate. The aforementioned tactile sensor also describes a technique for calculating the coordinates of the load applied to the plate, irrespective of its location on the plate, from the outputs of the strain gages on the individual supports and to provide a continuous electrical readout of such coordinates.
The aforementioned tactile load transducer, although capable of providing a continuous electrical readout of the magnitude and location of the sensed tactile load, is limited in compactness for any given desired level of forced sensitivity, by the distance between supports for the sensing plate and the bending stiffness of the plate. Where it is desired to provide a tactile load transducer or sensor having a high degree of load sensitivity yet have the capability to withstand relatively high loads, the plate must of necessity be relatively stiff. A load plate which is itself stiff in bending requires, therefore, enough distance between supports to provide high enough bending strains to enable the strain gages to give an adequate signal for light tactile loads or low level plate deflection. The aforementioned multiply supported plate tactile sensor thus is inherently limited in its compactness, or, stated otherwise, is bulky and not capable of compact design for a given load sensitivity application where size is of paramount importance.
Thus, it has long been desired to provide a way or means of reducing the size of a tactile load sensor or transducer for robotic operator applications without sacrificing the capability for withstanding heavy contact loads, yet retaining the sensitivity to small contact loads.